Abstract

Inhibition of angiotensin converting enzyme(ACE) in presence of captopril(C), lisinopril(L) and enalapril(E) were investigated in testis and epididymis of sheep using Hip-His-Leu as substrate. Captopril, lisinopril and enalapril were competitive inhibitors of the enzyme from both tissues. Differences in the I5o and K values using these three inhibitors reflects the affinities of these inhibitors for the ,~CE. Ih addition, the relative potencies of captopril, lisinopril and enalapril were different for testicular ACE(C > L > E) and epididymal ACE(L>C >E). This observation suggests differences between the active sites of the testicular and epididymal ACE which may reflect on their functions in vivo.